Enhanced performance and fouling resistance of cellulose acetate forward osmosis membrane with the spatial distribution of TiO2 and Al2O3 nanoparticles

BACKGROUND Novel nanocomposite membranes with spatial distribution of nanoparticles (NPs) were fabricated for forward osmosis (FO) applications. In this work, TiO2 and Al2O3 NPs were used as hydrophilic additives in order to improve the performance and fouling resistance of cellulose acetate (CA) FO membrane. RESULTS Attenuated Total Reflection Fourier Transform Infrared (ATR‐FTIR) and x‐ray diffraction (XRD) analyses confirmed the successful incorporation of the NPs into the synthesized membranes. The specific reverse salt flux (SRSF) of the TiO2 modified membrane was reduced from 0.88 to 0.56 g L−1, which was attributed to enhanced hydrophilicity, porosity, and the simultaneously improved water and salt permeability coefficients. After the evaluation of CA membranes with various contents of TiO2 NPs, Al2O3 NPs were added to the membrane structure as a secondary additive under the optimized content of TiO2 NPs. Al2O3 NPs have a higher dispersion in the membrane sublayer beneath, which can affect the hydrophilicity and surface charge of the membranes. Al2O3 and TiO2 modified membranes showed the lowest values of contact angle and zeta potential in neutral pH, which was 56.7°and − 68.4 mV, respectively. This membrane showed a water flux (WF) of 15 L m−2h−1 and an SRSF of 0.36 g L−1 when using 1 mol L−1 NaCl as a draw solution. The fouling behavior of sodium alginate on the neat and modified membranes was also investigated, and the results showed a reduced fouling propensity and a superior fouling reversibility in the modified membranes. CONCLUSION Based upon these findings, using low‐density hydrophilic NPs in the membrane structure can fabricate membranes with more hydrophilicity, excellent FO performance, and high organic fouling resistance. © 2020 Society of Chemical Industry